1. Technical Field
The present disclosure relates to current setting circuits such as current minors, and more particularly, to voltage and temperature invariant current setting circuits such as those used to control the gain in HBT (heterojunction bipolar transistor)-based designs.
2. Background
Current mirrors are used to accurately set currents in circuits. In multi-stage amplifier circuits that are HBT (heterojunction bipolar transistor)—based designs such as that shown in FIG. 1, the currents from the current mirrors are used to set the gain in the various stages and the overall circuit. In order to accurately control the gain, and therefore the output amplitude, especially in limiting amplifiers, the current should be set accurately and should not vary with bias or temperature (within the design specification of bias variation (typically +/−5%) and temperature variation (about −5° C. to about 85° C.)). If the current is not stable with temperature and bias, the output amplitude will undesirably vary with these parameters.